Top 250+ Solved Control of Electric Drives MCQ Questions Answer
Q. Which of the following motors is preferred for boom hoist of a travelling crane?
a. Single phase motor
b. Synchronous motor
c. A.C. slip ring motor
d. Ward-Leonard controlled D.C. shunt motor
Q. A wound rotor induction motor is preferred, as compared to squirrel cage induction motor, when major consideration is
a. slop speed operation
b. high starting torque
c. low windage losses
d. all of the above
Q. Which of the following motors has series characteristics ?
a. Shaded pole motor
b. Repulsion motor
c. Capacitor start motor
d. None of the above
Q. Which of the following happens when star-delta starter is used ?
a. Starting voltage is reduced
b. Starting current is reduced
c. Both (A) and (B)
d. None of the above
Q. For a D.C. shunt motor which of the following is incorrect 7
a. Unsuitable for heavy duty starting
b. Torque varies as armature current
c. Torque-armature current is a straight line
d. Torque is zero for zero armature current
Q. For which of the following applications motor has to start with high acceleration?
a. Oil expeller
b. Floor mill
c. Lifts and hoists
d. Centrifugal pump
Q. Which of the following types of motor enclosure is safest ?
a. Totally enclosed
b. Totally enclosed fan cooled
c. Open type
d. Semi closed
Q. While selecting motor for an air conditioner which of the following characteristicsis of great importance ?
a. Type of bearings
b. Type of enclosure
c. Noise
d. Arrangement for power transmis¬sion
Q. The diameter of the rotor shaft for an electric motor depends on which of thefollowing ?
a. r.p.m. only
b. Horse power only
c. Horse power and r.p.m.
d. Horse power, r.p.m. and power factor
Q. Which of the following alternatives will be cheaper ?
a. A 100 H.P. AC. three phase motor
b. Four motors of 25 H.P. each
c. Five motors of 20 H.P. each
d. Ten motors of 10 H.P. each
Q. The cost of an induction motor will increase as
a. horsepower rating increases but r.p.m. decreases
b. horsepower rating decreases but r.p.m. increases
c. horsepower rating and operating speed increases
d. horsepower rating and operating speed decreases
Q. In series motor which of the following methods can be used for changing the flux per pole ?
a. Tapped field control
b. Diverter field control
c. Series-parallel control
d. Any of the above
Q. Word Leonard controlled DC Drives are generally used for..... excavators
a. Light duty
b. Medium duty
c. Heavy duty
d. All of the above
Q. ......... is preferred for automatic drives
a. Synchronous motors
b. Word Leonard controlled DC motors
c. None of the above
d. Any of the above
Q. The load cycle for a motor driving a power press will be .........
a. Variable load
b. Continuous
c. Continuous but periodical
d. Intermittent and variable load